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Spring Bulbs After Bloom
by Leonard Perry
by Leonard Perry


In extension I serve as an advisor and consultant to the greenhouse and nursery industry, primarily in Vermont but throughout the region and beyond as well.

I give presentations on my research to the industry, and to home groups. In Research, my focus is "herbaceous perennial production systems".

His website is at  Leonards zone of gardening: home with my trials, generally USDA 4a. Campus in Burlington is 5.

June 1, 2008

Once spring flowering bulbs finish bloom, proper handling and care of perennial ones will help them to bloom again next year. The first question to answer is, which of your bulbs are perennial? This may be difficult with some tulips, most of which are treated as annuals.

Chances are, if your bulbs grew and bloomed this spring, they are hardy in your area. If they should have been hardy but didn’t come up or bloom, there could be several reasons. If the soil is too wet (bulbs like good drainage), they could have rotted. Something could have eaten them, above or below ground. Perhaps they started growing last fall, or early in the spring, only to have the buds killed by cold.

A couple rules apply to all bulbs in addition to providing them with good soil drainage. When planting, hopefully you added some bulb fertilizer or source of phosphorus (for healthy roots). Just as leaves emerge in spring, and just after bloom, are both are good times to apply more bulb fertilizer. If a granular form, don’t get on the leaves The key is to provide nutrients then as the leaves are making food for next year.

The second rule is to let the leaves die back naturally. If they are unsightly and fall over, try clipping tips back by a third to a half. Daffodil leaves, if not too many bulbs, can be bent over and tied in a knot or with a rubber band. If you have room, plant some annual flowers in front or in between to hide the dying bulb leaves. These leaves are key to producing the food, and so healthy bulbs, for next year.

You can, and should, cut off flower stalks after bloom, especially if they start to form seeds. You want all the bulb energy to go into next year’s bulb, not seed production.

If you must dig up spring bulbs, either to make room for annual flowers, or for other reasons, just make sure you leave the leaves on. Digging and transplanting often will make them die back faster. If you want to place the bulbs in a temporary holding area, or “heel them in”, to replant next fall, just make sure you mark them so you can find them come fall! An easy way to do this is to just “pot” the bulbs in a large pot with soil, compost, or soil-less medium where you know exactly where they are once the leaves die off.

If bulbs are becoming too crowded, as often happens with large daffodil clumps, or are blooming much less than in previous years, perhaps they need dividing. Dig and shake the soil off bulbs after bloom, leaving leaves attached if not died off already. Bulbs should separate naturally, otherwise plant back ones still joined together. Don’t forcibly pry bulbs apart.

Tulips are a bit different. If you’re like me, if you got 50 beautiful tulip blooms the first year you may have gotten only five the next and none the next, perhaps not even leaves. Most of the tulips you find and buy and love are hybrids. Once they reach several years old, the stage in their life in which they produce the biggest flowers and the stage we buy, they split after bloom into many smaller bulbs. If you’ve dug up tulips after the leaves start dying in early summer you may have noticed this. This is their means of multiplying naturally, and a trait of course bulb growers love and often select them for. So these bulbs will not generally bloom again, so treat them as annuals.

A few groups of hybrids, notably the Darwins, Emperors and some Triumphs, don’t split and so will come back for many years. You’ll find these marked in catalogs and stores as perennial or for “perennializing”. Some plant tulips deeper in fall, nine inches or more deep instead of the usual five or six inches, and claim this helps make them last more years, possibly from cooler soil temperatures.

I don’t mind treating most my tulips as annuals, as I like to try new varieties each year and don’t have the space for many, and they are so beautiful after a long winter that I find they are worth it. But, if you do want to try and keep the “non-perennial” tulips, they must have all the following. -- If the bulbs have already split when you dig them, you will need to nurse the baby bulbs for several years until they are large enough to bloom. -- Tulips need a long, cool spring to generate lots of plant food, and soil rich in nutrients. -- Dry tulips quickly when dug, and store over summer with lots of air circulation in warm to hot temperatures, not cool. Keep out of direct sunlight as this can scorch the bulbs.

These conditions mimic the ones in the tulips’ native habitats in the foothills of the Himalayan mountains, or the steppes of eastern Turkey. I’m just glad the Dutch, with over 400 years experience producing these bulbs and precisely controlled temperature and humidity chambers, have figured how to copy these conditions and provide us with such a welcome treat for spring and a new growing season.

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